The present invention refers to apparatus for feeding successive coils of strip to an unwinding station, particularly an unwinding station of a tandem rolling mill, comprising a transfer carriage, a vertically movable support, actuator means for moving the support vertically, at least two driven rollers mounted on the support for supporting a coil of strip, the driven rollers being radially spaced apart and rotating around respective parallel axes, and means for moving the transfer carriage from a coil entry station to an unwinding station.
A known method of feeding successive coils of strip to an unwinding station, specifically to an unwinding station of a tandem rolling mill, employs an apparatus consisting of a transfer carriage movable between an entry station and the unwinding station, a double-acting piston-cylinder actuator with a vertical axis mounted on the carriage, a fork-shaped coil support having two vertical arms carrying driven rollers at their upper ends, the support being carried and guided for movement vertically by the transfer carriage. At the entry station the fork-shaped support is lifted by its piston-cylinder actuator to receive and support a coil of metal strip on its driven rollers. Following this, the support is lowered by means of its actuator and the transfer carriage is moved linearly until it reaches a position adjoining the unwinding station, where it is arrested and a preliminary unwinding of the strip is effected. A portion of this strip is manipulated in a known fashion and fed for example into the first stand of a rolling mill or held in waiting until the terminal portion of the strip from the coil previously fed to the unwinding station has been exhausted.
An unwinding station generally consists of a support carriage hereinafter called a "coil box", having two vertical arms with idler rollers mounted on their upper ends and a double-acting oleodynamic piston-cylinder actuator with a vertical axis arranged to lift and lower the vertical arms or the whole coil box. The idler rollers are radially spaced apart and rotatable about respective axes parallel to the axes of rotation of the driven rollers of the transfer carriage. In their upper position the idler rollers of the coil box are lower than the driven rollers of the transfer carriage coil support when the support actuator is retracted. In a position adjacent the coil box and downstream from this in relation to the feed direction of the coils, a number of damper rollers are provided, supported in an arcuate arrangement such that the rollers may circumscribe a portion of the external surface of a coiled strip loaded onto the coil box.
It is moreover known that the coils of strip which arrive at the entry station may have the strip wound either in a tight or a slack fashion. When a tightly wound coil is handled to the unwinding station, the coil is supported by means of a pair of expansible mandrels, rotatably supported by a supporting structure conveniently positioned at the unwinding station, the mandrels being inserted by known oppositely acting means into the hollow cylindrical core of the coil. When a slack coil is fed to the unwinding station, then on account of the non-uniform nature of the strip unwinding process, expansible mandrels are not used to support the coil, but the coil is simply supported by the idler rollers of the coil box and laterally restrained by containing plates brought up to the opposite sides of the coil.
In an apparatus of the aforementioned kind, when slack coils of strip are to be fed to an unwinding station, it is necessary to transfer a slack coil from the transfer carriage, held in the preliminary unwinding position, to the coil box.
At present the transfer of such slack coils is effected by means of an angular displacement of the whole transfer carriage around one of its longitudinal axes parallel to the axis of rotation of the driven rollers of the fork-shaped coil support. Following this angular displacement, the coiled strip falls, with a partial rotation about its longitudinal axis, onto the idler rollers of the coil box, its descent being arrested by the damper rollers referred to above. At this point, in the case of a slack coil, the lateral containing plates will have been brought up to the coil and the unwinding of the strip may be completed.
This known system for feeding a slack coil to a strip unwinding station suffers from the considerable technical drawback that the transfer of the coils by falling from the transfer carriage to the coil box may cause damage to the strip to be rolled considerably straining also the structure of the coil box and of the damper rollers.
The object of the present invention is to provide a coil feed apparatus which enables a slack coil of strip to be fed conveniently to an unwinding station, while ameliorating the drawbacks associated with previously known apparatus of this type.